Backless Booster recommendation

[ctbarts]

We need to re-configure our use of seats and I am looking for some help. Here are the stats:

DS Age 9, 70 lbs and 54 inches currently in Monteray (which i love!)
DS Age 6, 45 lbs and 47 inches currently in Britax PW
DD Age 4, 37 lbs and 42 inches currently in MA

I need to give our Britax PW to the babysitter for DD as I think it will be the easiest seat for the babysitter to use correctly and be able to move easily in and out of her car. Not perfect for a 4yr old, but I do not trust the baysitter to install a convertable and it is 2 short trips a week. I am going to give DS who is 6 the Monteray and I want to get a backless for DS who is 9. He will appreciate this as he is one of the only of his friends that still even sit in a booster.

All 3 kiddos primarily ride in my 2006 Oddy.

What are the recommendations for a not too pricey backless booster. I am not sure I want to spend for the Clek though they sound great. The narrower the better as sometimes I need to get 3 across in the 3rd row and whenever I put a Graco TB back there it is too wide.

Thanks for in advance for the wisdom!!!

[Joolsplus2]

This is supposedly pretty narrow (Harmony Literider) http://www.walmart.com/catalog/product.do?product_id=10992661 and the Ambassador on that page (and cheap in all their stores or at Kmart) is light and cheap and fairly narrow under the armrests for buckling.
Combi Dakota is my kids' favorite booster by far, but it's a bit wide, and there's a $20 Harmony at Toys R Us, I forget the name of it, but it's boxy and larger than the LiteRider, better for bigger kids.
:)